This invention relates to laser apparatus and more particularly, but not exclusively, to metal vapour lasers.
Laser apparatus generally requires that, in addition to the material which is, or is to form, the laser active medium, a buffer gas is included in the discharge tube to enable sufficient gas pressure to be maintained for laser action to be possible. Typically, the buffer gas must be continuously pumped through the discharge tube so that contaminants are removed and gas pressure maintained against losses. The apparatus required to ensure that sufficient gas flows through the discharge tube is relatively complex and physically bulky, requiring external pumps, pipes and valves.